1-(4-amino-2-quinazolinyl)-piperidines and derivatives thereof containing in the piperidine-4-position "alkyl. . . alkoxy. . . hydroxy, hydroxyalkyl. . . phenyl, benzyl (and) 4-phenyl-4-carboxylic acid alkyl ester" are "hypotensive agents" according to Pat. No. 3,511,836 and 3,635,474. Surprisingly, the compounds according to this invention, containing the lactam-nitrogen atom in the piperidine-3 or 4-position, exhibit superior hypotensive and antihypertensive activity by way of the .alpha.-blocking mechanism, and a lesser tendency towards the development of tolerance.